Jack Healy and Michael Paulson

Huntington Beach, California: Their children have been sent home from school. Their families are barred from birthday parties and neighbourhood play dates. Online, people call them negligent and criminal.

But in California, anti-vaccine parents whose children have endured bouts of whooping cough and chickenpox largely defended their choice to raise their children on natural foods, essential oils and no vaccinations.

"There is absolutely no reason to get the shot," said Crystal McDonald, whose 16-year-old daughter was one of 66 students sent home from Palm Desert High School for the next two weeks because they did not have full measles immunisations.

After researching the issue and reading information from a national anti-vaccine advocacy group, Ms McDonald said she and her husband, a chiropractor, decided to raise their four children without vaccines.

The anti-vaccine movement can largely be traced to a 1998 report in a medical journal that suggested a link to autism but was later proved fraudulent and retracted. Today, the waves of parents who shun vaccines include some who still believe in the link. There is also a particular subculture of largely wealthy and well educated families, many living in palmy enclaves around Los Angeles and San Francisco, who are trying to carve out "all-natural" lives for their children.

"Sometimes, I feel like we're practising in the 1950s," said Dr Eric Ball, a paediatrician in southern Orange County, where some schools report that 50 to 60 per cent of their kindergartners are not fully vaccinated and that 20 to 40 per cent of parents have sought a personal-beliefs exemption to vaccination requirements.

Two of Dr Ball's patients are unvaccinated girls who became sick with the measles last week, although they had not been at Disneyland in Anaheim, California, and it was unclear exactly how they had been infected

"Our patients are really scared," Dr Ball said. "Our nightmare would be for someone to show up at our door with the measles."